Sludge silo

ABSTRACT

The invention relates to a silo for sludge, especially sewage sludge, comprising a sludge-receiving part ( 12 ), a feeding part ( 16 ), said feeding part being located above the sludge-receiving part ( 12 ) and communicating with said sludge-receiving part ( 12 ) via a inlet ( 14 ), and a sludge-discharge device. Said sludge-discharge device is located in the lower area of the sludge-receiving part, and can preferably be connected to a pipeline system. According to the invention, a separator device ( 18 ) for removing foreign bodies is located in the area of the feeding part ( 16 ) so that the sludge which is temporarily stored in the silo can easily be used later on. Said separating device for removing foreign bodies ( 18 ) has a sieve grate ( 20 ) covering the inlet ( 14 ) and at least one counter-surface ( 22 ) positioned above said sieve-grate ( 20 ). Said sieve-grate and said counter-surface are able to move in relation to each other as sludge pushes through the sieve openings of said sieve-grate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a silo for sludge, especially sewage sludge,comprising a sludge-receiving part, a feeding part in communicating withsaid sludge-receiving part via an inlet, and a sludge-discharge device.

2. Description of the Related Art

Sludges which are temporarily stored in silos of this type are generallytransported from the silo via a pipeline system to a disposal location,for example to a incineration facility. In order to prevent theentrainment of foreign bodies along with the sludge in the pipeline,which can lead to blockages in undefined areas thereof, it is known toprovide incorporated sieves at various locations in the pipeline system,which respectively retain foreign bodies depending on the sieve size. Inorder to prevent a clogging of the sieves, these must be removed andcleaned at relatively short time intervals.

SUMMARY OF THE INVENTION

Beginning therewith, it is the task of the invention to provideprecautionary measures in a silo for sludges and sewage sludges, whichmake it possible to dispense with the labor-intensive sieve devices inthe down-stream equipment and systems.

The inventive solution is based upon the concept, that if a separatingdevice for foreign bodies were to be located in the feeding part of thesilo, the sludge withdrawn through the sludge discharge device would bein better condition for a problem-free further transport through thepipeline system. Since in sludges, such as sewage sludges which have asolids content of up to 70%, the foreign bodies are embedded in thesludge and cannot be separated from the sludge purely using sieves, itis proposed in accordance with a preferred embodiment of the invention,that the foreign body separating device has a sieve-grate covering theinlet and at least one counter-surface position above the sieve-grate,which sieve-grate and counter-surface are moveable in relation to eachother as sludge pushes through the sieve openings of the sieve-grate.The foreign bodies, partially still soiled with sewage sludge, areretained by the sieve-grate and can either be removed by hand ormechanically before the next charge of sludge is introduced into thefeeding part. For this it is useful when the foreign body separatingdevice includes at least one foreign body outlet provided on the side ofthe sieve-grate opposite to the sludge-receiving part.

In accordance with a further preferred embodiment of the invention, theforeign body separation device includes a feed frame supplied withsludge and bordered by raised sidewalls, which is so positioned orpositionable between the sieve-grate and the counter-surface, that thesieve-grate and/or the counter surface are moveable relative to eachother transverse to the frame opening. A first variation of thisembodiment envisions that the counter-surface is formed by the innersurface of a silo lid covering over the feed part, and that thesieve-grate is moveable by means of a preferably hydraulic drive throughthe feed frame which is provided fixed to the silo and in the directionof the silo lid. In order to make it possible to remove the sludgecontaminated foreign bodies from the sieve-grate, a slideable sweeper orrake can be provided, in this case slideable parallel to the uppersurface of the sieve-grate and in the direction of the foreign bodyoutlet, which sweeper or rake can be driven by motor or hydraulically,when the sieve-grate is situated displaced towards its end positionagainst the counter-surface.

In accordance with a related embodiment, a sieve-grate is provided fixedto the silo and covering over the inlet opening, while thecounter-surface is provided in the form of a push- or pressure-plate,which is displaceable from above through the feed frame in the directionof the sieve-grate, preferably by means of a hydraulic drive. In thisalternative embodiment there is preferably provided a feed frame whichis displaceable relative to the supply part and the sieve-grate, whichis open towards above and below, and which can be filled with sludge ata filling station situated on a base aligned with the sieve-grate andfrom which fill position it is moveable in the direction of thesieve-grate. For the transport away of the foreign bodies contaminatedwithin the sewer sludge, the feed frame, with raised pressure plate, canbe displaced relative to the sieve-grate in the direction of the foreignbody outlet. The foreign body outlet preferably exhibits in this case anoutlet opening which on its edges contacts the sieve-grate, via whichthe floor-side open supply frame is moveable with carrying along of theforeign bodies.

The hydraulic drive of the sieve-grate or, as the case may be, pressureplate occurs preferably using four simultaneously operable hydrauliccylinders engaging along the edge or corner area of the sieve-grate or,as the case may be, the pressure plate. Depending upon application, itis also possible to employ more or fewer hydraulic cylinders as thedrive aggregate.

A further advantageous embodiment of the invention envisions that thecounter-surface is formed by a wiper or skimmer surface perpendicular ordiagonal to the direction of the sieve-grate and spring biased againstthe sieve-grate, wherein the sieve-grate and the skimmer or wiper aremoveable relative to each other parallel to the upper surface of thesieve-grate. Preferably herein the sieve-grate is rotateable about acentral axis relative to or with respect to the at least one silo-fixedwiper or skimmer. To order to facilitate the transport of larger foreignbodies to the foreign body outlet, there is provided supplementally,according to an advantageous embodiment of the invention, an abutmentwall or stop for this type of foreign body at least in the closeproximity above the sieve grate, radially oriented, which at the sametime can function as the assembly or mounting wall for the wiper.Preferably, two wiper groups are provided separated from each otherthrough the rotation center point of the sieve-grate, which servetherefore, that the sludge situated on the rotating sieve-grate is wipedor stripped spring-biased in the right direction and thereby pressedthrough the sieve-grate. The rotating sieve-grate is preferablysurrounded by a jacket fixed to the silo, which includes at least oneopening serving as foreign body outlet, which for control of acharge-wise foreign body output is preferably formed closeable orlockable.

The foreign body outlet can in all above-described variations open intoa foreign body chamber, which can be acted upon with water for removalof the sewage sludge from the foreign bodies and can be connected via asewage sludge conveyor section with the sludge receiving part of thesilo.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in greater detail onthe basis of the drawings and the embodiments illustrated therein inschematic manner. There is shown:

FIGS. 1a and b—the feed part of the silo for sewage sludge with closedsilo lid and lowered sieve-grate in vertical section and in top view.

FIGS. 1c and d—the feed part of the silo represented according to FIGS.1a and b with opened silo lid, raised sieve-grate and partially advancedclearing-out pusher.

FIGS. 2a and b—the feed part of an embodiment of the invention deviatingfrom that shown in FIG. 1, with a silo with sieve-grate fixed to thesilo, vertically displaceable push-plate and sideways slideable feedframe in a partial sectional side-view and a top view;

FIGS. 3a and b—the feed part of a further alternative embodiment of theinvention of a sewage sludge silo with rotating sieve-grate and wipersor strippers in a vertical section and a top view.

DETAILED DESCRIPTION OF THE INVENTION

The silo shown sectionally in the drawings is designed for theintermediate storage of sewage sludges with a solid component of up to70%. The silo 10 is comprised essentially of a sludge-receiving part 12,a feeding part 16 located above the sludge-receiving part 12 andcommunicating with the sludge-receiving part via a large surface inletopening 14, a slude-discharge device located in the lower area of thesludge-receiving part 12 and not shown, and a separator device 18 forseparation of foreign bodies brought in by the supplied sludge andpositioned at the height or elevation of the feed part 16. Foreignbodies contained in the sludge, such as screws, stones, and the like,can lead to disruptions in the pipeline systems down-stream of the siloas well as facilities such as mixing drums, dryers, or incineratordevices, which problems are avoided when using the separator device 18.

The foreign body separator devices 18 shown in the three illustratedembodiments according to FIGS. 1, 2, and 3 have in common a largesurface inlet opening 14 situated above the rigid sieve-grate 20 and atleast one counter-surface 22 provided above the sieve-grate, which aremoveable relative to each other under the throughput pressure of sludgethrough the openings of the sieve-grate 20. The three illustrativeembodiments further have in common a foreign body outlet 24 provided onthe side of the sieve-grate 20 opposite to that of the sludge-receivingpart 12 via which, after the pushing through of the sludge through thesieve-grate, the foreign bodies contaminated with sewage sludgeremaining on the upper side thereof can for example be removed to anoutwardly lying foreign body chamber 26. For cleansing of sludge fromthe foreign bodies the foreign body chamber can be acted upon withwater, and therefrom resulting sewage sludge can be returned to thesludge-receiving part 12 of the silo.

In the embodiment shown in FIG. 1, the separation device 18 includes afeed frame 28 fixed to the silo and bordered by raised sidewalls, inwhich the sieve-grate 20 can be raised and lowered in the direction ofthe arrows 30′, 30″ with the aid of the hydraulic cylinders 32. Thecounter-surface 22 is therein formed by the inner surface of the silolid 34 in its closed condition (FIGS. 1a and b). The filling of the feedpart 16 with sewage sludge is accomplished by a not-shown transporttruck from ramp 36 with a lowered sieve-grate 20 and opened silo lid 34.The feed part 16 is so dimensioned, that it can just receive a transporttruck-load of sewage sludge. After the filling process, the silo lid 34is brought to the closed position shown in FIGS. 1a and b and thesieve-grate 20 is subsequently moved, with the aid of the hydrauliccylinder, in the direction of the arrow 30′ 30 in the direction of thecounter-surface 22. Thereby the fine particulate or pasty sludgecomponents are pressed through the sieve-grate 20 into thesludge-receiving part 12, while the larger foreign bodies 26 containedwithin the sludge remain on the upper side of the sieve-grate 20. Afterreaching the upper end position of the sieve-grate 20 (FIGS. 1c and d),the silo lid 34 is opened in the direction of the arrow 38 withhydraulic means so that the foreign bodies situated on the sieve-grate20 are accessible from the outside. They can either be removed manuallyor, with the aid of a motor driven wiper 40, can be carried out in thedirection of the arrows 42, 44 to the solid body outlet 24 and to thesolid body chamber 26. After retraction of the clearing wiper 40 andlowering of the sieve-grate 20 to its lower end position, the feed part16 is available for a further charge of sludge.

In the embodiment shown in FIGS. 2a and b the separation device 18includes a silo-fixed sieve-grate 20′, while the counter-surface 22 isprovided on a pressure plate 46 which can be raised and lowered viahydraulic cylinders 32′ in the direction of the double arrows 30′, 30″.Further, feed frames 28′ are provided there, which in the area of feedpart 16 are slideable sideaways with respect to the silo 10 in thedirection of the arrows 54′, 54″ from a fill station 48 to a pressstation 50 and from there to a discharge station 52. In the fill station48, the supply frame which is upwardly and downwardly open, stands upona base 56 on the same plane as the sieve-grate 52 and can be filled withsewage sludge from ramp 36 by a transport truck. The full feed frame 28′is then pushed in the direction of the arrow 54′ with raised pressureplate 46 to the press station 50. There the sludge is pressed throughthe sieve-grate 20′ under displacement of the pressure plate 46 in thedirection of the arrow 30′ with the aid of the hydraulic cylinder, untilonly the sewage sludge contaminated foreign bodies remain on thesieve-grate. After lifting out of the pressure plate 46 out of the feedframe 28, this can be pushed or displaced in the direction of thedischarge station 52 with taking along the foreign bodies. Thereby theforeign bodies carried along through the foreign body outlet 24 reachthe outside. After return of the feed frame 28′ from the dischargestation to the fill station a further charge of sludge can beintroduced.

In the illustrative variation shown in FIGS. 3a and b, the separatordevice 18 exhibits a sieve-grate 20″ rotating in the direction of thearrow 58 by means of the rotational driver 60, while thecounter-surfaces 22 are formed by the wipers 62 of which the wipersurfaces lie diagonally in the direction of the sieve-grate against thesieve-grate 20″. The sieve-grate 20″ is positioned on the silo radiallyover the radial guide rollers 74 and axially over the axial guiderollers 76, of which respectively a plurality is provided on the silojacket and distributed about the circumference. The sieve-grate 20″ issurrounded by a jacket 64 fixed to the silo, which includes two radialopenings 68 lying diametrically opposite to each other, each formingrespectively one foreign body outlet 24 closeable with a flap 66. Theforeign bodies which remain upon the upper surface of the sieve-grate20″, which do not pass through the sieve openings 69 of the sieve-grate20″, ultimately end up radially outwards as a result of the action ofcentrifugal force and are retained there by a foreign body catcher 70and upon opening of the flaps 66 are conveyed into the foreign bodyoutlet 24. Further, there are provided here two radially orientedabutment or stop edges or walls 72 fixed to the silo close to and abovethe sieve-grate 20″, via which, due to the rotating sieve-grate 20″,through which larger foreign bodies stopped by the rotating sieve-grate20″ and directed radially outwards. The stop walls 72 simultaneouslyserve as the stops for the wipers 62.

In summary, the following is to be concluded: The invention relates to asilo for sludge, especially sewage sludge, comprising a sludge-receivingpart 12, a feeding part 16, said feeding part being located above thesludge-receiving part 12 and communicating with said sludge-receivingpart 12 via an inlet 14, and a sludge-discharge device. Saidsludge-discharge device is located in the lower area of thesludge-receiving part, and can preferably be connected to a pipelinesystem. According to the invention, a separator device 18 for removingforeign bodies is located in the area of the feeding part 16 so that thesludge which is temporarily stored in the silo can easily be used lateron. Said separating device for removing foreign bodies 18 has asieve-grate 20 covering the inlet and at least one counter-surface 22positioned above said sieve-grate 20. Said sieve-grate and saidcounter-surface are able to move in relation to each other as sludgepushes through the sieve openings of said sieve-grate.

What is claimed is:
 1. Silo for sludges with a sludge-receiving part(12), a feeding part (16) positioned above the sludge-receiving part(12) and in communication therewith via a large surface area inletopening (14), a sludge outlet located in the lower area of the sludgereceiving part (12), and a separating device (18) for separating foreignbodies from sludge provided at the inlet side, wherein said separatingdevice (18) is provided in the feeding part (16), wherein theforeign-body separating device (18) includes a sieve-grate (20, 20′,20″) positioned above the inlet opening (14) and at least onecounter-surface (22) positioned above the sieve-grate, said sieve grateand counter-surface moveable relative to each other to push sludgethrough the sieve openings of the sieve-grate, wherein the foreign bodyseparating device (18) includes a feed frame (28, 28′) having an openingfor receiving sludge and including a raised sidewall, which feed frameis so positioned or positionable between the sieve-grate (20, 20′) andthe counter-surface (22), that the sieve-grate and the counter-surfaceare moveable relative to each other perpendicular to the frame opening,and wherein the counter-surface (22) is formed by an inner surface of asilo lid (34) covering the feed part (16), and that the sieve-grate (20)is displaceable through the feed frame (28), which is provided fixed tothe silo, in the direction of the silo lid (34) by drive means (32). 2.A silo according to claim 1, wherein the foreign body separating device(18) includes at least one foreign body outlet (24) provided on the sideof the sieve-grate (20, 20′, 20″) opposite to the sludge-receiving part(12).
 3. A silo according to claim 1, wherein the foreign bodyseparating device (18) comprises a wiper (40) moveable parallel to theupper surface of the sieve-grate (20) in the direction of a foreign bodyoutlet.
 4. A silo according to claim 3, wherein the foreign body outlet(24) opens into a foreign body chamber (26).
 5. Silo according to claim4, wherein the foreign body chamber (26) can be acted upon by water forcleansing of sewage sludge from the foreign bodies, and is connected viaa sewage sludge conveyor part with the sludge-receiving part (12).
 6. Asilo according to claim 1, further comprising a hydraulic drive havingfour simultaneously operable hydraulic cylinders (32, 32′) engaging inthe edge area of the sieve-grate (20).